Alternating-current arc lamp



(No- Model.)

G. WESTINGHOUSE, Jr. ALTERNATING CURRENT ARG LAMP.

' No. 428,435. v Patented May 20,1890.

lllill|I|Illllllllllllllllllllllllllll|IHIIHIII| llllll III I IIXIHHHIIIIIIIlllllllllllllllllllllllllllllllllllHllllllllllllllll UNITED STATES ATENT OFFICE.

GEORGE WESTINGHOUSE, JR, OF PITTSBURG, PENNSYLVANIA.

ALTERNATlNG-CURRENT ARC LAMP.

SPECIFICATION forming part of Letters Patent No. 428,435, dated May 20, 1890,

Application filed March 19, 1890. Serial No.344,487. (No model.)

To all whom it may concern.-

Be it known that I, GEORGE WEsTING- HOUSE, .Ir., a citizen of the United States, re-

siding in Pittsburg, in the county of Alleof arc lamps designed to be operated by alternating electric currents.

The purpose of the invention is to provide a lamp of this character which will burn a long time Without requiring attention, and in which the light developed by the current passing from one electrode to the other will be utilized to the best advantage.

It has been proposed to employ broad flat carbons presenting extended edges to each other for use in arc lamps. Such carbons are especially useful in connection with alternating electric currents, and it is found in practice that an are formed by such a current travels to and fro along the confronting edges of the carbons, and the consumption of the carbon causes them to present wedge-shaped edges. In the operation of an arc lamp of the ordinary type by continuous current a crater is formed in the upper electrode, and this serves to a greater or less extent as a reflector, casting the light downward. hen an alternating current is used with carbons of the ordinary character, or of the flat type having extended edges, no such crater is formed, and more or less of the rays of light may escape. This objection I overcome by making the upper carbon thicker than the lower carbon, and it may be somewhat shorter than the lower carbon for the reason that it will not usually be eaten away quite so rapidly.

In the accompanying drawings there is illustrated an arc lamp having extended confronting edges designed to be operated by alternating currents.

Figure 1 is an elevation of the lamp. Fig. 2 is a section through 00 cc, Fig. 1. Fig. 3 is a side View of the electrodes.

Referring to the figures, A represents the frame of the arc lamp, and any suitable controlling mechanism may be placed within the case B. The particular character of this mechanism is not essential to the present invention and it need not be described here. Any suitable well-known apparatus may be adopted. The carbons are represent-ed at C 0 The upper carbon C is thicker than the lower carbon 0 and therefore its heated edge serves during the operation of the lamp as a reflector for casting downward rays of light which would otherwise be lost.

I claim as my invention 1. In an alternating-current arc lamp, confronting electrodes having extended edges, the upper electrode being of greater thickness than the lower.

2. The combination, in an arc lamp, of a lower flat carbon of a given thickness and an upper fiat carbon presenting an extended edge to the lower carbon and of greater thickness than the lower carbon.

In testimony whereof I have hereunto subscribed my name this 11th day of March, A. D. 1890.

GEO. WESTINGHOUSE, JR.

Witnesses:

CHARLES A. TERRY, JAMES \V. SMITH. 

